共查询到20条相似文献，搜索用时 454 毫秒
1.
用不同方法进行发动机噪声源识别的研究 总被引：9，自引：0，他引：9
发动机噪声源识别对于制定发动机降噪措施十分重要 ,而像油底壳、气门罩、前齿轮室盖等罩壳类零件通常是发动机的主要噪声源 .本文用铅覆盖法和表面振动测量法对一台六缸工程机械用柴油机进行了表面噪声源识别的研究 ,得到了罩壳类零件按噪声能量大小的排列顺序 ,文中首先在半消声条件下利用铅覆盖技术测量了这些罩壳类零件的声功率 ,然后又研究了它们的振动特性 ,并通过表面振动速度的面积时间均方值预测了其声功率 .两种方法的测量结果吻合较好 ,说明了它们在工程领域应用的有效性 相似文献
2.
Acoustic signals from diesel engines contain useful information but also include considerable noise components.To extract information for condition monitoring purposes, continuous wavelet transform (CWT) is used for the characterization of engine acoustics. This paper first reviews CWT characteristics represented by short duration transient signals.Wavelet selection and CWT are then implemented and wavelet transform is used to analyze the major sources of the engine front's exterior radiation sound. The research provides a reliable basis for engineering practice to reduce vehicle sound level.Comparison of the identification results of the measured acoustic signals with the identification results of the measured surface vibration showed good agreement. 相似文献
3.
Acoustic signals from diesel engines contain useful information but also include considerable noise components. To extract information for condition monitoring purposes, continuous wavelet transform (CWT) is used for the characterization of engine acoustics. This paper first reviews CWT characteristics represented by short duration transient signals. Wavelet selection and CWT are then implemented and wavelet transform is used to analyze the major sources of the engine front's exterior radiation sound. The research provides a reliable basis for engineering practice to reduce vehicle sound level. Comparison of the identification results of the measured acoustic signals with the identification results of the measured surface vibration showed good agreement. 相似文献
4.
A novel sound quality simulation approach was proposed to optimize the acoustic performance of a four-cylinder diesel engine. Finite element analysis, single-input and multiple-output technology, flexible multi-body dynamics, and boundary element codes were used to acquire the hexahedron-element model, experimental modal frequencies, vibration velocities, and structurally radiated noise of the block, respectively. The simulated modal frequencies and vibration velocities agreed well with the experimental data, which validated the finite-element block. The acoustic response showed that considerable acoustic power levels existed in 1500–1900 Hz and 2300–2800 Hz as the main frequency ranges to optimize the block acoustics. Then, the optimal block is determined in accordance with the novel approach, which reduces the overall value, high-frequency amplitudes, and peak values of acoustic power; thus, the loudness, sharpness, and roughness decline to make the sound quieter, lower-pitched, and smoother, respectively. Finally, the optimal block was cast and bench-tested. The results reveal that the sound quality of the optimal-block engine is substantially improved as numerically expected, which verifies the effectiveness of the research approach. 相似文献
5.
针对常规降噪方法应用于柴油机缸盖振动信号降噪时,自适应差且需要根据噪声环境人为调整参数的问题,在传统EEMD算法基础上提出一种改进的EEMD降噪算法,并将其应用于柴油机缸盖振动信号处理。首先对原始信号进行预处理,其次利用总体经验模态分解（EEMD）算法在非线性、非平稳信号处理时的自适应特性,分解原始信号得到各阶本征模态分量,经Savitzky-Golay平滑滤波,再将噪声占主导的高频分量进行阈值去噪,最后得到干净的本征模态分量进行重构。仿真实验和实测结果表明,在输入信号12dB的多种输入信号工况下,改进EEMD算法去噪后信噪比为17.1,比现有去噪方法提升14%。 相似文献
6.
刘成武郭小斌 《福建工程学院学报》2020,(6):518-523
为了研究结构几何参数及铺层参数改变对碳纤维复合板的振动声辐射特性影响,利用有限元/边界元法计算了碳纤维复合材料板的振动声辐射特性参数,并以降低结构振动噪声为目标对其进行了优化分析。研究表明:加筋、增加筋数和增加铺设层数能降低结构的辐射噪声。3 种铺层角度中,[0°/90°/45°]辐射噪声最低。在第一阶波峰处,优化后声功率值相比优化前减少了大约4 dB。研究结果可为降低结构辐射噪声提供理论依据。 相似文献
7.
Study of engine noise based on independent component analysis 总被引：1，自引：0，他引：1
HAO Zhi-yong JIN Yan YANG Chen 《浙江大学学报(A卷英文版)》2007,8(5):772-777
Independent component analysis was applied to analyze the acoustic signals from diesel engine. First the basic prin-ciple of independent component analysis (ICA) was reviewed. Diesel engine acoustic signal was decomposed into several inde-pendent components (ICs); Fourier transform and continuous wavelet transform (CWT) were applied to analyze the independent components. Different noise sources of the diesel engine were separated, based on the characteristics of different component in time-frequency domain. 相似文献
8.
A hybrid of ensemble empirical mode decomposition and empirical mode decomposition (EEMD-EMD) is introduced to diagnose the valve-slap vibration signal,which is relative to the dominant combustion knock vibration signal given out by a diesel engine around the top dead center (TDC).The time-frequency representations of intrinsic mode functions (IMFs) decomposed by EEMD-EMD are obtained by adaptive generalized S transform (AGST).A type 493 diesel engine was used for the experiment,and the result indicates that the valve-slap of the diesel engine is serious,and the vibration frequencies are higher than the combustion knock.With EEMD-EMD-AGST approach,the valve-slap can be identified by the vibration analysis of the diesel engine. 相似文献
9.
Virtual design and performance prediction of a silencing air cleaner used in an I.C. engine intake system 总被引：3，自引：0，他引：3
INTRODUCTION The primary function of an intake system is firstly to efficiently channel fresh air to the engine,and secondly to minimize intake noise emissions.There are a number of current approaches for devel-oping a more realistic method to improve intake sys-tem design.The objectives include more effective silencing performance to meet increasingly severe legislative targets for reduced noise on the one hand,with optimized engine performance and fuel economy accompanied by improvements… 相似文献
10.
刘成武郭小斌 《福建工程学院学报》2020,(4):375-380
利用有限元法与边界元法结合对薄板进行振动声辐射特性分析,研究了薄板结构在简谐力作用下表面声压分布状况,分析了不同边界条件、材料以及加筋形式等因素对薄板结构振动声辐射特性的影响,并对简支矩形薄板厚度进行了优化。研究表明,边界约束的增加会导致薄板刚度变大,进而导致薄板辐射声功率与辐射效率随之改变?不同材料对结构的辐射声功率均有影响,而对辐射效率影响很小?加筋对薄板声辐射特性影响显著,十字型加筋形式减震降噪效果最好?对薄板厚度进行优化,优化后薄板辐射声功率级下降了4.29dB。 相似文献
11.
以车用490QA柴油机为样机改造成液化石油气-柴油双燃料发动机,在分别燃用纯柴油和液化石油气-柴油双燃料的情况下,实行了相应工况的对比试验,得出了两者的动力性、经济性、尾气排放以及噪声等性能参数,总结出工作特性。结果表明双燃料发动机在动力性、燃料消耗、碳烟排放和噪声性能都优于原柴油机。 相似文献
12.
高利军 《邢台职业技术学院学报》2006,23(1):67-69
针对输液管道振动大,噪声污染严重的问题,本文结合振动理论、声场理论、应用有限元以及边界元方法对输液管道受激振动的噪声辐射过程进行研究,并提出了一种新的低噪声管道结构设计方法。 相似文献
13.
《天津大学学报(英文版)》2015,(4)
Targeting the non-stationary characteristics of diesel engine vibration signals and the limitations of singular value decomposition(SVD) technique, a new method based on improved local mean decomposition(LMD), SVD technique and relevance vector machine(RVM) was proposed for the identification of diesel valve fault in this study. Firstly, the vibration signals were acquired through the vibration sensors installed on the cylinder head in one normal state and four fault states of valve trains. Secondly, an improved LMD method was used to decompose the non-stationary signals into a set of stationary product functions(PF), from which the initial feature vector matrices can be formed automatically. Then, the singular values were obtained by applying the SVD technique to the initial feature vector matrixes. Finally, slant binary tree and sort separability criterion were combined to determine the structure of multi-class RVM, and the singular values were regarded as the fault feature vectors of RVM in the identification of fault types of diesel valve clearance. The experimental results showed that the proposed fault diagnosis method can effectively extract the features of diesel valve clearance and identify the diesel valve fault accurately. 相似文献
14.
蒋汪萍 《中国教育技术装备》2011,(30)
汽车振动是影响舒适性的主要因素之一,如何采用有效的技术手段测量分析汽车的振动,日益受到人们重视。采用LMS多分析系统,测试分析发动机振动随发动机转速变化的关系。结果发现,发动机二阶振动是引起车内噪声的主要原因。通过测试悬置系统隔振性能,为进一步提高系统隔振性能提供依据。 相似文献
15.
Fault diagnosis of valve clearance in diesel engine based on BP neural network and support vector machine 总被引：1，自引：0，他引：1
Based on wavelet packet transformation(WPT), genetic algorithm(GA), back propagation neural network(BPNN)and support vector machine(SVM), a fault diagnosis method of diesel engine valve clearance is presented. With power spectral density analysis, the characteristic frequency related to the engine running conditions can be extracted from vibration signals. The biggest singular values(BSV)of wavelet coefficients and root mean square (RMS)values of vibration in characteristic frequency sub-bands are extracted at the end of third level decomposition of vibration signals, and they are used as input vectors of BPNN or SVM. To avoid being trapped in local minima, GA is adopted. The normal and fault vibration signals measured in different valve clearance conditions are analyzed. BPNN, GA back propagation neural network (GA-BPNN), SVM and GA-SVM are applied to the training and testing for the extraction of different features, and the classification accuracies and training time are compared to determine the optimum fault classifier and feature selection. Experimental results demonstrate that the proposed features and classification algorithms give classification accuracy of 100%. 相似文献
16.
The paired comparison (PC) is an easy and effective way to distinguish the nuances among sound stimuli of diesel engine in sound quality subjective evaluation. However, the PC method is inefficient for the subjective evaluation of large quantities of stimulus or to rank the results of overall perception of sound stimuli. To overcome the shortcoming of the PC method, this paper presents a comprehensive evaluation method of diesel engine sound quality based on the PC method, uniform design sampling (UDS), and the improved analytic hierarchy process (AHP). An hierarchical tree of comprehensive evaluation models of diesel engine sound quality is constructed and simplified through UDS to ensure that the sound sample size is in the application range of the PC method or the grouped paired-wise comparison (GPC) method. An improved AHP is developed by introducing a new method calculating the relative weight based on evaluators’ preference order instead of the traditional 1–9 scale method, which reduces subjective liberty and difficulty of the consistency of the judgment matrix meeting the requirement, and the requirements of evaluators’ specialized knowledge. With three diesel engines’ noise stimuli as example, a realization of sound quality comprehensive evaluation based on UDS-AHP method with the GPC method is introduced. The results show that the proposed subjective comprehensive evaluation method can accurately provide the ranks of the sound stimuli over all subjective perception with a significant decrease of the evaluation workload. 相似文献
17.
有限元分析是柴油机零部件结构强度分析中一种实用、可靠的方法。以某柴油机连杆为研究对象,对其建立实体模型,并利用有限元分析的软件平台,对连杆强度进行分析。在应用有限元方法对柴油机连杆进行静力分析过程中,研究连杆在最大受压状态和最大受拉状态的两个极限受力状态情况,为连杆的改进和设计提供可靠的依据。 相似文献
18.
《天津大学学报(英文版)》2015,(4)
To understand the vibration noise behaviors of amorphous metal alloy core distribution transformer(AMACDT), a 10 k VA prototype was tested under no-load and short-circuit conditions, respectively. The vibration characteristics were described when rated voltage was applied to the secondary side, and the primary side was connected with different load resistances. The largest amplitude positions on the upper bracket and tank surfaces were recorded by vibration sensors arranged on the surface. A data-acquisition platform was set up for signal measurement. The vibration amplitude related to frequency was discussed, and experimental results indicated that the position with the largest amplitude accrued in the middle of the upper bracket and tank surface, at phases a and c, respectively. The experimental results suggest that magnetostrictive and electrodynamic forces play a major role in exciting the vibration noise. At the same time, some rib-reinforcements were welded on the upper bracket and tank surfaces to lessen the vibration energy, which reduced the noise. 相似文献
19.
For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration
and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached
to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of
connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism.
In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and
rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed
subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are
separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces
to improve the engine’s noise vibration and harshness performance. 相似文献
20.
This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method and the surface sound pressure by Rayleigh integral,and expressed the sound radiation power of the structure in a positive definite quadratic form of the Hermitian with an impedance matrix.The ADS analysis of the plate was thus translated into the analysis of structure dynamic sensitivity and ... 相似文献